Administrative barriers to social insurance program take-up are pervasive, including in subsidized
health insurance. We conducted a randomized controlled trial with Massachusetts’ Affordable
Care Act marketplace to reduce these barriers and other behavioral frictions. We find that a
“check the box” streamlined enrollment intervention raises enrollment by 11%, more than
personalized reminder letters (7.9% increase) or generic reminder letters (4.5% increase). Effects
are concentrated among individuals eligible for zero-premium plans, who faced no further
administrative burdens of setting up payments. Producing this enrollment effect through premium
reduction would cost about $6 million in subsidies, highlighting the importance of these burdens.